It has previously been proposed to provide lamps for automotive vehicles, associated, for example, with a reflector. Modern lamps, such as halogen incandescent lamps, discharge lamps and the like, operate at temperatures which place a severe thermal strain on the base. U.S. Pat. No. 4,609,977, of which the co-inventors hereof are also co-inventors, as well as German Utility Model No. 85 22 797, describes a lamp-base assembly, for combination with a reflector, in which a two-component base is used to receive a metallic sleeve in which the lamp bulb itself is retained. In a preferred embodiment, the base and a connecting portion are made of plastic material which, after assembly, are welded together for example by ultrasonic plastic welding, to form an essentially inseparable unit.
Use of ultrasonic heating to connect base elements requires additional working steps which, further, use energy due to the welding processes used. The thermal loading of the lamp requires, however, an arrangement in which the portion or part closest to the lamp uses a plastic material which is highly heat-resistant, whereas the component remote from the lamp bulb can use a cheaper and less heat-resistant plastic. Forming a junction by ultrasonic heating of the high heat-resistant and the lower heat-resistant plastic is difficult.
The quality of such a junction is impaired by the differences in melting temperatures of the different plastic materials.